Was vs Were

[AhoyMcCoy]

I think I know the difference and when to use one and not the other, but I don't know why one is wrong!

For example: a friend said "was you thinking about me on Friday?" And I corrected "it's were you thinking about me?", but I can't for the life of me explain why her way is incorrect and mine is correct! So, any easy explanations of when to use 'was' and when to use 'were'?

It's just learnt language for me, I think.

I was
You were
He was
We were
They were

I suppose learning other languages made this more obvious to me as many of them have a plural or formal form of you, but in English it is just the way the verb "to be" works. I don't think there is a situation where "you was..." or "was you...." would be correct.

HTH.

it is just the way the verb "to be" works

Yes, this.

The same reason you say "I run" and not "I runs"

You corrected a friend's spoken English?

One thing to watch out for is the subjunctive where "was" changes to "were", eg "if I were a really picky pedant, I'd correct spoken English as well as written" used for hypothetical constructions.

Isn't it just a case of turning it round - you would say "you were" not "you was" so "were you" is correct not "was you". Or are you questioning why it's "you were" in which case no idea, it's just the way that verb works! But I'm a bit about you correcting a friend's English!